What would be the touch up paint on stock aluminum wheels on a 2006 Subaru Legacy Outback??

They dont sell touch up paint for the wheels, if you really want it done right call a business that does alloy wheel repair. Typically they come to you, take the wheel off the car, sand her down, add a filler, contour the filler, sand it, then color match the paint and airbrush it back on then clear coat it. Costs about $100 last time I checked.

I would have the wheels stripped and polished.

Buy decent spray silver and paint BOTH wheels on one side. You nor anyone else will see the left/right slight mismatch.